Patent GB-472406-A (GB)
Title: Improvements relating to power transmission systems embodying hydraulic couplings
IPC: F16H47/08
Filed: 1936-03-24
Abstract: 472,406. Hydraulic transmission of power. SINCLAIR, H. March 24, 1936, No. 8826. [Class 69 (ii)] The invention relates to the actuation of a torque-reducing control member for varying the torque transmission capacity of a power transmission system embodying a hydraulic coupling of the kinetic type. The control member may be a brake for arresting or restraining rotation of the driving machine or of the driving part or of the driven part of the coupling ; the control member may alternatively comprise means for altering the torque transmission capacity of the coupling itself, as for example a slidable ring-valve or equivalent device for controlling the circulation of liquid in the working circuit, or a filling or emptying valve for varying the liquid content of the working circuit. In one use, as e.g. in vehicles, the actuation of the control member is controlled at will; the movement of the control member is derived from the movement of one of the elements of the coupling, irrespective of whether the other of said elements is rotating, although in some forms rotation of the said other element may accelerate the movement of the control member. The arrangement may be such as to brake the runner, or even to impart to it a backward torque relieving the drag-torque and facilitating the engagement of gears associated with the coupling. In one form, Fig. 1, a ring valve 19 for controlling the circulation in the working circuit carries a nut 23 ; the valve is slidably mounted on pins 22 carried by the runner 13 so that the nut 23 rotates therewith ; the nut engages a screwed sleeve 25 rotatably mounted on the driven shaft 14 and carrying a sun-wheel 29 meshing with a planet-wheel 30 journalled on a pin 32 carried by the casing 21 of the impeller 12 ; the gear 30 is integral with a second gear 31 meshing with a sun-wheel 33, rotation of which can be controlled by a brake band 35 actuated at will. The sleeve 25 is normallv constrained to rotate at the same speed as the driven shaft 14 by a spiral spring 36 connecting the two. In action, when the brake 35 is applied, the rotation of the impeller causes, through the epicyclic gearing, backward rotation of the sleeve 25, thus moving the ring valve into the circuit ; if the runner is stationary the movement of the valve will be slow, said movement being faster if the runner is rotating. When the valve is fully closed, the brake 35 may slip, or be held on, in the latter case the backward rotation of the sleeve being imparted through the nut, which has now reached the limit of its travel, to the runner and driven shaft, thus relieving the drag-torque on the change-speed gearing 16 and facilitating the engagement of a gear, as for example, when the vehicle is stationary. When the brake 35 is released, the spring 36 which has been stressed, will return the valve to its inoperative position. In a modification, not illustrated, the gearing 29-33 is omitted, and a brake is arranged to act on the screwed sleeve to hold the latter stationary, so that rotation of the turbine will cause the valve to close ; eventually, the turbine and driven shaft will be braked by the sleeve through the nut, when it has reached the limit of its travel, but no relief of drag-torque is obtained. In a further modification, not illustrated, the sleeve is normally constrained by a spring to rotate with the impeller but can be held stationary by a brake, so that rotation of the impeller will cause the valve to close ; no relief of drag-torque or braking of the driven side is obtained. In another use, as e.g. in ships' steering gear, comprising a steam turbine coupled through a hydraulic coupling with a hydraulic pump driving a reversible hydraulic motor operatively connected with the helm, or in a Ward-Leonard winding-engine driven by a steam turbine or a Diesel engine through a hydraulic coupling, the actuating mechanism of the control member is responsive to reversal of slip in the coupling, the arrangement being such that when the impeller over-runs the runner the control member is inoperative whereas when the runner over-runs the impeller the control member is automatically rendered operative to reduce the over-running torque or at least to reduce the over-running torque transmitted to the driving machine. In one form, Fig. 2, the driven shaft 14a is screw-threaded at 41 and carries a nut 42 carrying a throttling ring-valve 19a and splined in a part 44 rotated through a slipping clutch 46 by the casing of the impeller 12a. With the impeller over-running, the parts are as shown, - the nut (being at the limit of its travel on the shaft) rotating with the runner and the clutch slipping ; when the runner over-runs, the clutch becomes operative to rotate the nut at the same speed as the impeller, and the valve is moved into circuit. In a modification, Fig. 3, the coupling is of the core-tube emptying type, the outflow of liquid being controlled by a ring- valve 19b actuated automatically by screw-andnut mechanism 41b, 42b similar to that described above ; a constant circulation is ensured by a leakage port 19<1> in the ring-valve, the normal liquid content being adjusted by an inlet valve 50. In a further modification, Fig. 4, the coupling is of the core-emptying scoop-tube type, the inflow of liquid being controlled by an inlet valve 66 actuated automatically by screw-and-nut mechanism 41c, 42c; the normal liquid content is adjusted by an inlet valve 50c. In addition to or instead of the inlet valve 66, the coupling may be provided with peripheral exhaust ports controlled by a ring- valve actuated automatically by the screw- and-nut mechanism ; alternatively, the latter may automatically actuate a brake 72 acting on the driven shaft or on any other part of the transmission system, as e.g. on the driving machine. The Provisional Specification describes a modified form of the arrangement shown in Fig. 1, in which the coil spring 36 is omitted, and after the ring-valve has been inserted into the circuit by application of the brake 35, said brake is released and the sun-wheel 33 clutched to the impeller casing, whereby the sleeve 25 rotates at the same speed as the impeller, the epicyclic gear being rendered solid, so that the valve is moved out of circuit if the impeller is over-runriing, but remains in if the turbine is over-running.